Process for removing cyclopentadiene from forerunnings



Patented July 29, 1947 PROCESS FOR REMOVING CYCLOPENTA- DIENE FROM FORERUNNINGS Joseph H. Wells and Philip J Wilson, Jr., Pittsburgh, Pa;, assignors to Carnegie-Illinois Steel Corporation, a corporation of New Jersey N Drawing. Application November 29, 1943,

Serial No. 512,253

2 Claims. 1 In accordance with the present invention, there are provided certain improvements in the pro- 'duction of an organic compound which can be used in the production of varnishes and similar practically no compounds which boil above 60 C., such as benzene which boils at 80 C. The above temperature range is to be considered as illustrative only, and not as limiting, and other temperature ranges may prove to be suitable. This fraction which contains the cyclopentadiene is called forerunnings.

The next step in the process is the reaction of the cyclopentadiene in the forerunnings with coating compositions. 5 maleic anhydride to produce endomethylene- In accordance with the present inventionysuch 3,6-tetrahydropht c anhydride Which is p valuable product is obtained from a low-boiling clpitated in the form of colorless crystals. The by-product present in the light oil produced in a reaction which occurs is as follows: Icy-product coke oven plant.

Thus, cyclopentadiene is one of the low boiling l0 3 compounds present in the light oil which is pro- H H duced in such a by-product coke oven plant, and OTGQO H0 O C o forms the starting material for the production I 0 +H 0 ll HCH I 0 of the particular compound obtained in the op- 4 H I 20 eration of the present invention, this compound 15 H H H being a crystalline compound identified as endo- H methylene-3,6-tetrahydrophthalic anhydride.

As has been indicated above, cyclopentadiene fi th? a ae ggir'firilltgfitfifil'i is one of the low-boiling compounds present in anhydride the light oil which is produced in a by-product I coke oven plant. Cyclopentadiene boils at 415 g f g ggg g gg gg g g gy g ggfigg gg C. and consequently is difficult to separate in the laboratory test and usually a little less than pure p from the light oil distillaifim' other would be required for complete reaction with the P P compounds present m the boll" cyclopentadiene is used in order to insure that mg points close to that of cyclopentadiene. Thus the product does not Containany of this unre carbon disulfide boils at 46.3 C., and some of the acted reagent amylenes 100,11 between and BY of The reaction may be carried out in various 2. fractionatlng column with very high eificiency ways;

. and careful control some separation may be S 30 One procedure is to add the maleic anhydride cured but the operatmg cost due to the hlgh crystals to the forerunnings and stir together flux ratio and the large intermediate fracPions until the reaction is complete. The reaction is render? this method separation prehibltiver strongly exothermic so that cooling must be proe aslde from the imtlal cost the mstana" vided in order to prevent loss of cyclopentadiene tion. by vaporization. For a fraction which boils In accordance W h th pr nv i it initially at 20 C. a temperature of not over 15 C. has been discovered that this cyclopentadienei is recommended can be removed from the light oiland recovered I any of th foregoing procedures, the next in the form ofauseful derivative,endomethylenestep is t filter t crystals of t 1 3fi-tetrahydlophthalic anhydride. The Process 3,6-tetrahydrophthalic anhydride from the liquid employed in accordance with the present inven- 40 by any suitable means, such as a plate and frame tion is, first, to fractionate the light oil so as to filter press. Some of the endomethylene-3,6- separate the .cyclopentadiene and the other ortetrahydrophthalic anhydride will be in solution garlic compounds which boil in t same g in the forerunnings, or thebenzene, respectively, perature range in a single fraction. This sepdepending on winch reaetlon m q has been aration may be carried out in a still equipped i portlon of the f recovered with a iractionating column. If a cut of all the distmmg off the SGIVem but is likely to be ompounds which boil between 20 C. and60 C. pure h h l separated.by P t1on due to 1mpur1t1es which may be dissolved in 15 taken for example 1t,W111Pntamub$ta1t1e11Y the solvent. After the endomethylene-3,6-tetraall of the cyclopentadiene m the light 011, but

hydrophthalic anhydride crystals are filtered from molten maleic anhydride; the latter can be returned directly to the absorbers.

Although the endomethylene-3,6-tetrahydrophthalic anhydride crystals which are produced by this process are of good quality and can be The process of the present inventicn'inay be illustrated by the following example:

From 1000 gallons of light oil there was separated gallons of forerunnings boiling up to 60 C. by distillation using a bubble platefrac- 6.6? gallons or 44.5 pounds of cyclopentadiene.

When 55 pounds of maleic anhydride were, added a to the forerunnings in an agitator kept.at atemperature not over 15" C. endomethylen'e-3fi tetrahydrophthalic anhydricle was produced in: the form of colorless crystals. By filtration using a plate and frame press 88 pounds of crystals were recovered.

The anhydride crystals which are produced can be reacted with glycerol or similar polyhydroxy alcohols to produce alkyd resins by processes which are commonly used in the resin industry.

The endornethylene 3,6 tetrahydrophthalic anhydride can exist in two stereoisomerie forms.- The cis-form is'the one which predominates in the product. It has a melting pointof 164C. Only very small amounts of the trans-form ocour in the product.

Although the product is identified herein by the term endomethylene-3,6-tetrahydrophthalic anhydride, other terminology has been used to identify this product in the literature. Thus it has been called 3,6-endomethylene-l,2,3,6-tetrahydrophthalic anhydride. (See F. C. Whitmore, Organic Chemistry, published in 1937.)

In the operation of the process of the present invention, maleic anhydride is not the only material that can be used in the reaction. Thus, instead of maleic anhydride, there may be used an acid anhydride of similar structure except that substituted for one or both of the hydrogen atoms are other organic groups, either aliphatic, aromatic, or both.

In fact,for maleic anhydride there may "be substituted any similar conjugated alpha-betauns'aturated carbonyl compounds which react with diolefins by What is commonly known to chemists as the Diels-Alder reaction, which is illustrated by the reaction indicated above herein.

Such compounds are the anhydrides of"u.nsatu'-' rated dicarboxylic acids, and are exemplified by the general formula Cnl-hngzoa, and inaddition 10 tionating column. The forerunnings contained 7 as further examples, all of these compounds being characterized by the group and all behaving similarly to maleic anhydride.

We claim: 1. The process for removing cyclopentadiene from a; forerunnings fraction with an endpoint distilling temperature of not more than degrees Cr obtained by fractionating the light oil produced in the by-product coking of coal, which comprises directly reacting the cyclopentadiene in the said forerunnings with an 04,8 unsaturated carbonyl compound containing the group cc=o while maintaining the reaction temperature at not morev than 15 degrees 0., thereby preventing any substantial polymerization of the cyclopentadiene, and recovering the resulting substantially pure reaction product by filtration.

21 A process for the production of substantially.

pure endometirvlene-3fi-tetrahydrophthalic anhydride which comprises directly reacting the cyclopentadiene contained in a iorerunnings fraction. having aniendpoint distilling. temperature of 'not. more than 60 degrees C. obtained by fractionation of light oil produced in the by-product cokingof coal, with maleic anhydride while maintaining, the temperature at not more than 15 degrees 0., thereby avoiding any substantial polymerization of. the cyclopentadiene, and recovering the resulting substantially pure reaction product by filtration. JOSEPH H. WELLS,

PHILIP J. WILSON, JR.

REFERENCES omen The following references are of record in the file "of this patent:

UNITED STATES PATENTS Number Name Date 25104;!)5'6 Stem-m; Jan. 11, 19st 2,-068;850 -E-llis Jan. 26,1937 139443731 Diels-Alder Jan. 23; 1934' FOREIGN PATENTS Nuniher f 7 Country. Date 38,810. GreatBritain ..Iu1ne.2, 1934 352,164 Great Britain July 9, 193.1

' "OT H F RE CES JournalAmer; Chem. Soc.','Feb-. 1941, pages 62'7 "industrial '&' Engineering Chem Jan. 1932; pages 49-50.

. Industrial.& Engineering Chemistry, volumeSO,

NDLJZ; F613,. 1938, pp. 169-172. 

